Teammates had to convince Judge to walk up the dugout steps to acknowledge the fans saluting him at Yankee Stadium.
Embarrassed by the attention, he managed four short waves with his right hand before heading back to the bench just three seconds later.
"They kind of told me: `You got to go out there. You got to go out there,'" he would later recall. "First curtain call. I hope it was a good one."
Judge had his second straight two-homer game in the 11-3 rout of Kansas City. On an unseasonably warm autumn afternoon, the Yankees won for the 16th time in 22 games during a playoff push that earned no worse than a wild card.
McGwire hit 49 homers for the Oakland Athletics in 1987, breaking the previous mark of 38 set by the Boston Braves' Wally Berger in 1930 and matched by Cincinnati's Frank Robinson in 1956.
Judge's nearly unprecedented power output has been a revelation for the Yankees. While there was never a question of the strength of the 6-foot-7, 282-pound Judge, there were doubts about whether he would be able to make contact often enough to justify a regular spot in the order.
In 2016, Judge made his MLB debut, hitting a home run in his first plate appearance, but he struck out in 42 of his 84 at-bats, hitting .179. He has included that batting average in his pregame notes throughout 2017.
In the first half of the season, Judge was the talk of baseball, hitting 30 home runs before the break to make the All-Star team. He won the Home Run Derby, and even commissioner Rob Manfred did not think it was out of bounds to speculate about Judge being the next face of the sport.
"The way he started, I thought he was going to hit 60, 70," Yankees catcher Gary Sanchez said through an interpreter.
But as if zapped by kryptonite, Judge slumped to a .179 average with seven homers and 16 RBIs from the start of the second half through Aug. 31, a whiff-a-thon that included 67 strikeouts in 44 games.
"I saw frustration," Yankees manager Joe Girardi said. "I didn't see him getting down. I never saw him stop working. I never saw him not believe in himself."
Judge revived to hit .307 with 13 homers and 26 RBIs in a stunning September, leaving him with a .283 average, 108 RBIs, an AL-leading 120 walks and a big-league-high 203 strikeouts. He has five homers in his past six games and four multihomer games this month.
"Everybody's going to say, 'Oh, the strikeouts.' But I think if I'm an owner or a GM, I'll take 300 strikeouts with the year he's putting up," Yankees third baseman Todd Frazier said.
The surge has vaulted Judge's name back into American League MVP contention. He is seemingly a lock to win AL Rookie of the Year.
Judge has homered against every AL opponent and his total is second in the majors to Marlins slugger Giancarlo Stanton's 57. Other contenders for the AL MVP award include Houston's Jose Altuve and Cleveland's Jose Ramirez.
"I'd rather be in a good position in the playoffs and holding up a World Series trophy than an AL MVP trophy," Judge said.
"We can honestly say that we're in this spot because of him," Yankees pitcher CC Sabathia said of Judge. "I think that's what an MVP is."
Judge has 90-degree power, pulling 22 homers to left, hitting 13 to center and sending 15 opposite-field shots to right, according to MLB's Statcast. His teammates never let him get down during the big slump.
"They kept pushing me, kept motivating me: 'Hey, man, you're going to get out of this. It's baseball. Keep doing your thing,'" Judge remembered, speaking after Monday's game in a pinstriped thumbs-down T-shirt.
In spring training, Judge almost wasn't named the starting right fielder. Despite a .931 OPS in exhibition games, the Yankees did not hand Judge the job over Aaron Hicks until the final days of spring training.
"He's handled it with grace and humility, and he's never lost who he is and his ability to change someone's day," Girardi said. "He's a natural-born leader for me. ... It's almost like he's a big brother. He watches out over everyone. He waits for the players to come off the field. You got the whole package."
Information from ESPN's Andrew Marchand and The Associated Press was used in this report.